Jhin's attacks are quite potent, but he runs out of ammo after the 4th shot. Use this window to jump him and burst him down.
Jhin is heavily team-reliant because of his unique kit and playstyle. He needs a durable front line to allow him to stand far back in fights, and needs allied crowd control to allow for easy followup with his skillshots.
Jhin's long range and zone control make him an excellent scout/sniper. Deep wards and the utility of Lotus Trap can use that range to pick out enemies alone in the jungle with the help of his team and the vision.
Dancing Grenade makes quick work of caster minions, even being able to one-shot all three of them with a single cast if Jhin has enough damage. Use this to your advantage if an enemy should ever come close to his minion wave. Use regular auto attacks to prime the wave for clearing, launch a strategic Dancing Grenade, and then land the final shot on an enemy champion. If both the grenade and final shot land, the enemy can take upwards of 800 damage in the mid-game.
Dancing Grenade prioritizes only the closest valid unit. It will neither prioritize low-health enemies nor enemy champions and it cannot bounce to a single enemy twice.
In this way, Dancing Grenade can be "aimed" by casting from exactly the right direction against the perfect number of targets. A skilled Jhin player will be able to land empowered grenades on champions, rather than simply casting against champions as the primary target. This is most powerful in the laning phase and less effective during fights.
Travel time for each bounce is calculated by the distance between targets. If the targets are far enough apart, you may have time to fire another autoattack, placing the target in execution range and increasing the power of the next bounce.
Enemies will not be Caught Out and marked for Deadly Flourish if they are too far out of range, while the spell is on cooldown, or when it has not been leveled at least once.
Deadly Flourish has an instant or near-instant travel time, so you only need to account for its cast time when aiming.
Try to always store a Lotus Trap for escapes or cc combos. Periodically place traps in bushes and rivers to slow and deter potential ganks. Jhin can only hold 2 traps at once, and holding on to both will pause the recharge timer. Place the second trap as soon as it's available for maximum trap output.
All minions and monsters can trigger Lotus Trapsexcept for Baron Nashor (presumably because Baron cannot move). Traps placed on top of the Baron will bounce to a nearby location, similar to wards. Traps will activate underneath neutral monsters out of combat, but they will not become hostile until taking damage.
If two Lotus Traps are placed directly on top of one another, they will trigger simultaneously, allowing both traps to deal full damage at once (multiple traps are supposed to deal 65% damage). However, choosing to stack traps for the potential burst will mean that you can't use them as wards or to slow chasing enemies.
Using Curtain Call from far enough in lane enables it to cover the entire width of the lane, denying your victims the option of exiting its AoE.
Jhin is hindered by his mediocre attack range and low attack speed, so he can easily be bullied by faster high-burst enemies. However, Jhin can hold onto his empowered fourth shot for some time. Use that to your advantage as enemies will stay back when they see that it's available. Last hit with your abilities, which will reset Whisper's buff duration to keep enemies at bay for as long as possible and to stave off the reload time until you are safer, since reloading makes you vulnerable.
Jhin's ability to obtain very high bonus AD makes Deathfire Touch a viable option for him, as this mastery has a sizeable bonus AD scaling and it also provides extra damage while reloading. To boot, all four of Jhin's abilities can proc it.
Jhin's high potential attack damage also makes Warlord's Bloodlust an attractive choice. Jhin's tendency to build at least one item with the Energized passive provides further synergy, allowing Jhin to periodically heal and deal extra damage on a single attack. The healing from Warlord's Bloodlust is additionally increased on a critical strike, and this extra healing scales with additional critical damage, which is given by the passive of Infinity Edge. Warlord's Bloodlust is therefore an excellent choice if you want to increase your survivability, though you will lose the kill-securing power granted by Deathfire Touch.
Statikk Shiv is recommended to assist in Jhin's below-average wave-clear. It will allow him to save ammo and mana when clearing a wave.
Rapid Firecannon will help to assist his below-average turret sieging. It also provides a method of delivering a long-range, energized Final Shot crit for massive damage.
Infinity Edge will empower the Final Shot as well as any regular auto-attacks which may crit. However, the critical strike bonus damage is reduced. Infinity Edge will function with the Final Shot of Curtain Call for the normal 250% bonus damage.
Try to dodge Deadly Flourish when in a Lotus Trap or you'll be rooted in the damaging zone. Fast champions should always try to trigger Lotus Traps because they can run straight through the trap before it detonates. It is tempting to disarm the traps if you know where they are, but beware the potential of a bait.
Try to fight Jhin head-on when you're playing a champion who fares well in close-range or quick-paced combat. Jhin has little means to kite or to quickly burst without his fourth shot up, so if you can get in his face while he's reloading or on his first or second shot, you'll win the duel.
Even if you aren't good at melee or burst, it's always important to pay attention to his passive. The best time to go in on Jhin is when he's reloading, because he can't attack for a short time, and then needs 3 more slow attacks to ready his empowered crit. However, if Jhin is nearing his final bullet, you should disengage quickly or he can deal sudden, massive damage.
As against all champions who utilize bouncing projectiles, don't stand too near to allied minions or champions. When facing Jhin, this is especially important when allies are low on health, because a Dancing Grenade will deal extra damage if it bounces to you after killing them.
Deadly Flourish is a very narrow skillshot that can and should be dodged easily. Jhin will usually wait for his teammates to use their own crowd control abilities to land a guaranteed root from long distance, so his position should always be accounted for.
Tanky champions can be difficult for Jhin to deal with, as he relies on burst damage against low-armor, low-health targets. A tanky champion should always lead an advance towards Jhin, as they can block Deadly Flourish and all shots from Curtain Call, plus trigger any Lotus Traps without taking nearly as much damage as a squishy.
Braum is considered to be a strong pick against Jhin. First off, Jhin's below average mobility will give him a hard time avoiding Concussive Blows from getting stacked onto him by Braum and his teammates. This is especially difficult if Braum has an ally who can stack his passive quickly, such as Lucian. Second off, The majority of Jhin's damage output will be blocked by not only Unbreakable but even by Braum himself. Third off, Braum can scout and disarm Lotus Trap, walking over one and using Stand Behind Me to quickly leap to any of his allies.
Curtain Call deals increasing damage the lower its target is. This is known as an "execute." These are especially important to dodge if you aren't at full health, and if a shot needs to be blocked, they highest health ally should do it, even if they aren't a tank. The final shot of Curtain Call deals at least double the damage of the other shots, so if you aren't near full health, you should make sure to dodge this no matter what.
Jhin's fourth shot from both Curtain Call and Whisper deals high execute damage. Champions building high maximum health but low armor can take well over 1500 damage from either ability when weakened.
Zed can be a deadly counter to Jhin. The passive of his Death Mark grants a portion of the victim's total AD to Zed. This benefits fully from Jhin's insanely high AD, allowing Zed to easily reap over 70 bonus AD from Jhin in the late-game.